add inter-op tests

[smlng]

Currently test are only run with and against pycayennelpp, this is insufficient. We should run encoding and decoding tests against other libs from other programming languages to ensure interoperability, as it would likely appear in real world scenarios. For example, use an embedded C library on a sensor for encoding and pycayennelpp for decoding on a client, e.g. webapp or similar.

[amotl]

Hi Sebastian,

I recognized you becoming active on this code base again and I appreciate it very much. I should also spend some time on the Terkin Datalogger in order to give it some love again.

On the aspect of interoperability tests against C/C++ libraries, I believe Arduino CayenneLPP library conceived by @ElectronicCats - specifically @sabas1080 and contributors - is the most popular one in this space. The repository also contains a decoder implementation in JavaScript, see decoder.js.

Regarding interoperability tests with MicroPython, there is the MicroPython Unix port. It might be worth to look into that space how it could be leveraged to run some integration tests against.

On the matter of MicroPython on microcontrollers, vanilla MicroPython made great progress (currently on version 1.14, already supporting the new Raspberry Pi Pico). However, Pycom MicroPython unfortunately lacks behind and is still based on MicroPython 1.11. On this matter, I was specifically looking at the upgrade to Python 3.6+ on behalf of #70. While I didn't have time to check if that would break anything, according to your comments, the code base itself doesn't use any more modern Python features yet, right?

With kind regards,
Andreas.

cc @thiasB

[smlng]

@amotl the changes in #70 just reflect the fact that Python 3.6 is the oldest version still officially supported (until the end of 2021, that is). However, until now I'm not using any features or code specific to Python 3.6 or above, hence this lib should still work with Python 3.4 and 3.5, if required.

Regarding my activity here: the past year was different and other things kept me busy 😉 . I plan to invest some time to push ideas I have to move this project forward.